Thermoplastic polyurethane-regulated solid-state polymer gel for fast viologen-based all-in-one flexible electrochromic devices

Solid-state all-in-one FECDs are constructed using PEGDMA-TPU electrolyte. • FECDs achieve fast switching with 3.2 s coloring and 8.4 s bleaching. • FECDs realize dynamic patterns and 3.2 °C photothermal regulation. A key challenge in viologen-based solid-state all-in-one flexible electrochromic devices (FECDs) lies in that they display generally sluggish electrochromic response. In this work, flexible thermoplastic polyurethane (TPU) is incorporated into the cross-linked skeleton of poly(ethylene glycol) dimethacrylate (poly(PEGDMA)). By regulating the cross-linked network structure, the system is endowed with high-efficiency ion conduction and excellent mechanical flexibility. Viologen-based solid-state all-in-one electrochromic devices fabricated via this strategy exhibit superior comprehensive performance: rapid switching (3.2/8.4 s for coloration/bleaching), which is among the superior response times reported in relevant FECDs, high optical contrast (Δ T =81.9%), and excellent cycling durability (>87% retention after 1000 cycles) and reliable bending tolerance (negligible changes in CV curves after 1000 bending cycles). Moreover, the devices enable applications such as anti-counterfeiting and smart windows. Compared with conventional windows, a model house equipped with the smart window achieves a temperature reduction of 3.2°C under simulated solar irradiation within the time period of 30 minutes. This work provides robust support and lays a technical foundation for constructing fast-response viologen-based solid-state all-in-one FECDs. Download: Download high-res image (271KB) Download: Download full-size image